[Korsakoff's syndrome secondary to left thalamic bleeding]. / Síndrome de Korsakoff secundario a hemorragia talámica izquierda.

Korsakoff's syndrome is characterised by an important impairment in memory in comparison to other cognitive functions. Presence of confabulations is frequent but they are not characteristic of this syndrome. Alcohol abuse is the main cause of this syndrome but it also has been associated to other causes, like malnutrition or structural lesions. Although the role of thalamus in memory processing is well established, the development of confabulations in the setting of a thalamic lesion is poorly described in the literature. We present a 61 year-old hypertensive man, with an important impairment in anterograde memory, confabulations and acalculia after a left thalamic haemorrhage. Other cognitive functions were intact except a partial temporal disorientation. Thalamic dementia is generally caused by bilateral thalamic damage. Usually, all cognitive functions are impaired. As thalamus takes part in Papez's circuit, either thalamic nuclei or their connections lesions may originate memory impairment. However, although a relation between the presence of confabulations and connections from thalamus to frontal lobe lesions has been described, there is almost no evidence in the literature.

[Acalculia: its classification, aetiology and clinical management]. / Acalculia: clasificación, etiología y tratamiento clínico.

AIM: To carry out a review of the literature on the different neurological mechanisms involved in processing calculations, the injuries to brain structure that can result in acalculia and the clinical management of these patients. Development and conclusions. Acalculia is defined as the disorder affecting the ability to calculate that is acquired as the result of a brain injury. Despite being a frequent symptom and its association to numerous systemic and neurological diseases, no clear study protocol exists due to the fact that, first, it is usually accompanied by other, more important neurological symptoms and, second, it occurs in a very heterogeneous population, where clear differences can be seen according to the sociocultural level of the patient. Acalculia has been associated both to general alterations of the central nervous system and to others affecting local structures. Perhaps the most striking example of the former is the case of dementias, where it has even been suggested that it could be an early sign of Alzheimer's disease. With respect to the latter, the most notable are those affecting the left parietal lobe. In this article the following are discussed: 1) the different classifications that have been developed for the loss of the ability to calculate; 2) the involvement of the different structures of the nervous system in numeric processing, based on the associated structural lesions and on studies that have been conducted using functional tests and brain imaging; and 3) the different neuropsychological instruments that are available to study this capacity.

Acalculia: clasificación, etiología y tratamiento clínico / Acalculia: its classification, aetiology and clinical management

Objetivo. Realizar una revisión de la bibliografía sobrelos diferentes mecanismos neurológicos implicados en el procesamientodel cálculo, las lesiones estructurales cerebrales capaces deproducir acalculia y el manejo clínico de estos pacientes. Desarrolloy conclusiones. La acalculia se define como el trastorno adquiridode la habilidad de cálculo secundario a una lesión cerebral. A pesarde ser un síntoma frecuente y asociarse a múltiples enfermedadessistémicas y neurológicas, no existe un claro protocolo de estudiodebido, en primer lugar, a que suele acompañarse de otros síntomasneurológicos de mayor importancia y, en segundo lugar, a la granheterogeneidad de la población, existiendo claras diferencias segúnel nivel sociocultural del paciente. La acalculia se ha asociado tantoa alteraciones generales del sistema nervioso central como estructuraleslocales. De entre las primeras destacan las demencias,habiéndose llegado a sugerir que podría suponer un signo precoz dela enfermedad de Alzheimer. Respecto a las segundas, destacan lasque afectan al lóbulo parietal izquierdo. En este artículo se discute:1) las diferentes clasificaciones desarrolladas para la pérdida de lahabilidad del cálculo, 2) la implicación de las diferentes estructurasdel sistema nervioso en el procesamiento numérico, con base en laslesiones estructurales asociadas y a los estudios realizados mediantepruebas funcionales y de imagen cerebral, y 3) las distintasherramientas neuropsicológicas de las que disponemos para el estudiode esta capacidad

Aim. To carry out a review of the literature on the different neurological mechanisms involved in processingcalculations, the injuries to brain structure that can result in acalculia and the clinical management of these patients.Development and conclusions. Acalculia is defined as the disorder affecting the ability to calculate that is acquired as the resultof a brain injury. Despite being a frequent symptom and its association to numerous systemic and neurological diseases, noclear study protocol exists due to the fact that, first, it is usually accompanied by other, more important neurological symptomsand, second, it occurs in a very heterogeneous population, where clear differences can be seen according to the socioculturallevel of the patient. Acalculia has been associated both to general alterations of the central nervous system and to othersaffecting local structures. Perhaps the most striking example of the former is the case of dementias, where it has even beensuggested that it could be an early sign of Alzheimer’s disease. With respect to the latter, the most notable are those affectingthe left parietal lobe. In this article the following are discussed: 1) the different classifications that have been developed for theloss of the ability to calculate; 2) the involvement of the different structures of the nervous system in numeric processing, basedon the associated structural lesions and on studies that have been conducted using functional tests and brain imaging; and3) the different neuropsychological instruments that are available to study this capacity